Content-type: message/rfc822 Content-transfer-encoding: base64 Subject: a multipart message/rfc822 which has been base64-encoded

Content-Type: multipart/mixed; boundary="------------299A70B339B65A93542D2AE"

This is a multi-part message in MIME format.

Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit

That was a multi-part message in MIME format.